Computer file systems and/or file system protocols often use access control lists to specify the users, groups of users, etc. that can access a file or other object stored in the file system. Access control lists can specify the types of access and/or types of operations users can perform on a file or other object. In some instances, these types of access and/or operations can be referred to as permissions. For example, an access control list for a file can specify that a first user can read the file; a second user can read the file and modify the file; and a third user can read the file, modify the file, and execute the file. Many file systems allow permissions to be set individually for each file in the file system. In some implementations of file systems, an access control list is accordingly created for each file in the file system. This can lead to storing multiple access control lists that contain the same permissions. As the number of the files in an operating system and the number of users of that file system grow, the access control lists can occupy valuable storage space.